609 research outputs found

    Fuzzy adaptive resonance theory: Applications and extensions

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    Adaptive Resonance Theory, ART, is a powerful clustering tool for learning arbitrary patterns in a self-organizing manner. In this research, two papers are presented that examine the extensibility and applications of ART. The first paper examines a means to boost ART performance by assigning each cluster a vigilance value, instead of a single value for the whole ART module. A Particle Swarm Optimization technique is used to search for desirable vigilance values. In the second paper, it is shown how ART, and clustering in general, can be a useful tool in preprocessing time series data. Clustering quantization attempts to meaningfully group data for preprocessing purposes, and improves results over the absence of quantization with statistical significance. --Abstract, page iv

    "Unknown" Students on College Campuses: An Exploratory Analysis

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    Examines data from three campuses to identify college students falling into the "race/ethnicity unknown" category. Provides recommendations for increasing demographic accuracy, and measuring the success of underrepresented students in higher education

    Dependence of sediment sorting on bedload transport phase in a river meander

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    It is widely recognized nowadays that there are at least two different phases of bedload sediment transport in gravel‐bed rivers. However, the transition between these phases is still poorly or subjectively defined, especially at bends in rivers, where cross‐stream sediment transport can strongly influence changes in the texture of the transported sediment. In this paper, we use piecewise models to identify objectively, at two points in the cross‐section of a river bend, the discharge at which the transition between bedload transport phases occurs. Piecewise models were applied to a new bedload data set collected during a wide range of discharges while analysing the associated changes in sediment texture. Results allowed the identification of two well‐differentiated phases of sediment transport (phase I and phase II), with a breakpoint located around bankfull discharge. Associated with each phase there was a change in bedload texture. In phase I there was non‐dominance in the transport of fine or coarse fractions at a particular sampling point; but in phase II bedload texture was strongly linked to the position of the sampling point across the channel. In this phase, fine particles tended to be transported to the inner bank, while coarse sizes were transferred throughout the middle parts of the channel. Moreover, bedload texture at the inner sampling point became bimodal while the transport of pebble‐sized particles was increasing in the central parts of the river channel. It is suggested that this general pattern may be related both to secondary currents, which transfer finer particles from the outer to the inner bank, and to the progressive dismantling of the riverbed surface layer. Copyright © 2018 John Wiley & Sons, Ltd.info:eu-repo/semantics/acceptedVersio

    IC 4663: the first unambiguous [WN] Wolf-Rayet central star of a planetary nebula

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    We report on the serendipitous discovery of the first central star of a planetary nebula (PN) that mimics the helium- and nitrogen-rich WN sequence of massive Wolf–Rayet (WR) stars. The central star of IC 4663 (PN G346.2−08.2) is dominated by broad He II and N V emission lines which correspond to a [WN3] spectral type. Unlike previous [WN] candidates, the surrounding nebula is unambiguously a PN. At an assumed distance of 3.5 kpc, corresponding to a stellar luminosity of 4000 L⊙, the V= 16.9 mag central star remains 4–6 mag fainter than the average luminosity of massive WN3 stars even out to an improbable d= 8 kpc. The nebula is typical of PNe with an elliptical morphology, a newly discovered asymptotic giant branch (AGB) halo, a relatively low expansion velocity (vexp= 30 km s−1) and a highly ionized spectrum with an approximately solar chemical abundance pattern. The [WN3] star is hot enough to show Ne VII emission (T*= 140 ± 20 kK) and exhibits a fast wind (v∞= 1900 km s−1), which at d= 3.5 kpc would yield a clumped mass-loss rate of forumla= 1.8 × 10−8 M⊙ yr−1 with a small stellar radius (R*= 0.11 R⊙). Its atmosphere consists of helium (95 per cent), hydrogen (<2 per cent), nitrogen (0.8 per cent), neon (0.2 per cent) and oxygen (0.05 per cent) by mass. Such an unusual helium-dominated composition cannot be produced by any extant scenario used to explain the H-deficiency of post-AGB stars. The O(He) central stars share a similar composition and the discovery of IC 4663 provides the first evidence for a second He-rich/H-deficient post-AGB evolutionary sequence [WN] →O(He). This suggests that there is an alternative mechanism responsible for producing the majority of H-deficient post-AGB stars that may possibly be expanded to include other He-rich/H-deficient stars such as R Coronae Borealis stars and AM Canum Venaticorum stars. The origin of the unusual composition of [WN] and O(He) central stars remains unexplained

    Evolving protocols for research in equitation science

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    Within the emerging discipline of Equitation Science the application of consistent methodology, including robust objective measures, is required for sound scientific evaluation. This report aims to provide an evaluation of current methodology and to propose some initial guidelines for future research. The value of research, especially that involving small sample sizes, can be enhanced by the application of consistent methodology and reporting enabling results to be compared across studies. This paper includes guidelines for experimental design in studies involving the ridden horse. Equine ethograms currently used are reviewed and factors to be considered in the development of a riddenhorse ethogram are evaluated. An assessment of methods used to collect behavioral and physiological data is included and the use of equipment for measurements (e.g., rein-tension and pressure-sensing instruments) is discussed. Equitation science is a new discipline, subject to evolving viewpoints on research foci and design. Technological advances may improve the accuracy and detail of measurements, but must be used within appropriate and valid experimental designs

    A standard of care for individuals with PIK3CA ‐related disorders: an international expert consensus statement

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    Growth promoting variants in PIK3CA cause a spectrum of developmental disorders, depending on the developmental timing of the mutation and tissues involved. These phenotypically heterogeneous entities have been grouped as PIK3CA-Related Overgrowth Spectrum disorders (PROS). Deep sequencing technologies have facilitated detection of low-level mosaic, often necessitating testing of tissues other than blood. Since clinical management practices vary considerably among healthcare professionals and services across different countries, a consensus on management guidelines is needed. Clinical heterogeneity within this spectrum leads to challenges in establishing management recommendations, which must be based on patient-specific considerations. Moreover, as most of these conditions are rare, affected families may lack access to the medical expertise that is needed to help address the multi-system and often complex medical issues seen with PROS. In March 2019, macrocephaly-capillary malformation (M-CM) patient organizations hosted an expert meeting in Manchester, United Kingdom, to help address these challenges with regards to M-CM syndrome. We have expanded the scope of this project to cover PROS and developed this consensus statement on the preferred approach for managing affected individuals based on our current knowledge

    Shakespeare and the Senses

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    his article examines recent critical approaches to Shakespeare and the senses. Historicizing the senses has posed certain methodological challenges: what is the relationship between subjective sensory perceptions and broader cultural understandings of sensation? Does the sensate have a history? Recent work on each of the five senses demonstrates that the answer is yes. And, surprisingly, Shakespeare and his literary works are at the center of the field. As an important figure of the English literary canon, yet one about whom we know so very little, Shakespeare's sensory archive is both omnipresent and illusive. Shakespearean sensations thus provide a way of grappling with the larger methodological stakes of this field. This article examines a wide range of critical approaches to Shakespeare's sensory archive and ends by considering possible paths for further research. Publication cover image Volume6, Issue3 May 2009 Pages 726-740 Figures References Related Information Metrics Details © 2009 The Author. Journal Compilation © 2009 Blackwell Publishing Lt

    Structural analysis of pathogenic mutations in the DYRK1A gene in patients with developmental disorders.

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    Haploinsufficiency in DYRK1A is associated with a recognizable developmental syndrome, though the mechanism of action of pathogenic missense mutations is currently unclear. Here we present 19 de novo mutations in this gene, including five missense mutations, identified by the Deciphering Developmental Disorder study. Protein structural analysis reveals that the missense mutations are either close to the ATP or peptide binding-sites within the kinase domain, or are important for protein stability, suggesting they lead to a loss of the protein's function mechanism. Furthermore, there is some correlation between the magnitude of the change and the severity of the resultant phenotype. A comparison of the distribution of the pathogenic mutations along the length of DYRK1A with that of natural variants, as found in the ExAC database, confirms that mutations in the N-terminal end of the kinase domain are more disruptive of protein function. In particular, pathogenic mutations occur in significantly closer proximity to the ATP and the substrate peptide than the natural variants. Overall, we suggest that de novo dominant mutations in DYRK1A account for nearly 0.5% of severe developmental disorders due to substantially reduced kinase function
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